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Table of Content

    10 December 2014, Volume 25 Issue 23
    A New Type of Dynamic Vibration Absorber for Pipe System Vibration Suppression
    Chen Guo, Cheng Xiaoyong, Liu Minghua, Luo Yun, Hou Minli, Zhao Bin
    2014, 25(23):  3125-3131. 
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    A new spring type of dynamic vibration absorber for pipe system vibration suppression was designed. The absorber connected with the main system by bolted connections, and leaf spring and mass were used to constitute the spring-mass system. The parameters of the vibration absorber  were selected  firstly,  then the finite  element model of the pipeline system was set up to analyze the harmonic response between pre-and post installation of the damper; finally, experiments  were completed to confirm the system. The results show that: the vibration in the resonant frequency will be reduced 90% with the dynamic vibration absorber, the effects of block with the same mass as damper were compared, and the results show that vibration damping has a greater effect than that of mass. This designed dynamic vibration absorber can reduce pipeline vibration levels significantly, and have a good damping effect.

    Research on Ultrasonic Cutting Acoustic System of Machining Nomex Honeycomb Material
    Zhang Yundian, Xiao Jianxiong, Fang Liang, Lu Zhiping
    2014, 25(23):  3132-3136,3146. 
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    According to the principles of ultrasonic machining, a new type of CNC ultrasonic cutting spindle of cutting Nomex honeycomb materials was designed. The acoustic horn was designed by the four-end network method, and the acoustic horn was also analyzed and corrected by FEM. The finite element model of ultrasonic acoustic system was established and analyzed. According to the diagram, the displacement of horn flange changes little, the output amplitude is larger. The amplitude of the cutter was measured by laser detector, and was worked out a=22.37μm that meets the processing requirements. A large of experiments of cutting Nomex honeycomb materials using the ultrasonic cutting spindle was carried out, and the results are significant: smooth processing surface, high processing precision,  no dust in machining process.

    Optimization Method of VSR Process Parameters for Large Machine Tool Body
    Hu Min, Yu Changwu, Zhao Wanhua, Cun Huaying, Yuan Shengwan, Zhang Wenkai
    2014, 25(23):  3137-3142. 
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    A new method of achieving the best process parameters of VSR through modal simulation was proposed herein. Then the average stress elimination rate of the new process and the original process on the bed casting was compared. The experimental results show that, the average stress elimination rate of the new technology is as 65.1%, while the original process is as 38.5%. Besides, the stress value of one test point under the original process condition increases instead. The stress elimination rate of the new process is higher than that of the original process. The results verify the correctness of the optimization method of VSR process parameters for large machine tool body.

    Analyses of Position and Error for a Novel 3-RRRRR Parallel Micromanipulator
    Li Shihua, Ju Yanru, Ma Qixiang, Li Fujuan
    2014, 25(23):  3142-3146. 
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    The kinematics of a new parallel micromanipulator driven by piezoelectric ceramic was analyzed. The D-H method was used to make analyses on the position of a micro-platform and deducing the expressions of the micro-platform's inverse solution. On the basis of the error analyses on a single branch, a terminal error model was established, and the errors were analyzed. The research fruits have a certain guiding significance for the design and manufacture of 3-RRRRR parallel micro-mechanism.
    Identification Approach of Geometrical Parameters for Non-contact Five-coordinate Measuring Machine
    Fei Zhigen, Xu Xiaojie, Guo Junjie
    2014, 25(23):  3147-3150. 
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    Aiming at the exploited non-contact five-coordinate measuring machine with laser probe, its overall structure and working principles were introduced. The measurement mathematical model of such system was established by virtue of multi-body kinematics theory and homogeneous transformation. For the unknown geometrical parameters in this model, the identification approaches were proposed based on testing the physical basis. The experimental results show that the method is valid and feasible. The identification repeated errors of three system geometrical parameters are all within 2μm.

    Experimental Study of Saw-tooth Chip Formation in Hard Cutting of SKD11
    Jing Lulu, Chen Ming, An Qinglong
    2014, 25(23):  3151-3154,3159. 
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    Chips in hard cutting of hardened steel SKD11 were collected and observed by metallographic microscope and SEM; chip metallurgical textures and configuration under different cutting speeds were investigated. Dynamic shearing stress and temperature in adiabatic shear zones were discussed. Results show that in hard cutting of SKD11, saw-tooth chips are formed under both of low and high cutting speeds. Degree of segmentation increases with the increase of cutting speed. The saw-tooth chip formation could be due to fracture and adiabatic shearing; and with the increase of cutting speed, the chip formation mechanism changes from fracture to adiabatic shearing. During adiabatic shearing process, shearing stress develops as a quadratic curve, and cutting temperature shows distinct influence on the dynamic shearing stress. By increasing cutting speed, cutting temperature can be increased, which will weaken the hardening effect and reduce the maximum shear stress, cause occurrence of shearing instability and then reduce cutting force.

    Optimization and Analysis of Transition Curves for Roots of Universal Cross Shaft
    Chen Ke, Yin Lei, Chen Zhenhua
    2014, 25(23):  3155-3159. 
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    The double curvature arc, elliptic arc and streamline arc were proposed as transition curves for roots of universal cross shaft in order to reduce stress concentration, by searching transition curves with low stress concentration factor. And the formulas of transition curves for roots of universal cross shaft were established. The examples for the formulas of transition curves were carried out and the FEM analyses for the samples were implemented. The FEM analysis results indicate that the stress concentration is relieved by the three transition curves put forward. 

    T-Splines Trimming Approach for B-spline Surfaces
    Xue Xiang, Zhou Laishui
    2014, 25(23):  3160-3164. 
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    To solve the problem of trimmed surface definition and trimming boundary alteration in B-spline surface trimming approach, a new T-Splines trimming approach was proposed and was used for the surface trimming upon multilateral rectangular domain. After converting B-spline surface into a full-row-column T-Splines, a trimmed T-Splines was obtained by applying the local uniform refinement and removing control points of T-Splines. The trimmed T-Splines was built upon a multilateral T-Mesh with a complete surface definition, and the trimming boundary can be locally modified. Finally, the trimmed T-Splines was proved to be superior to the trimmed B-spline surface in surface definition and boundary alteration with a modeling example.

    Research on Defects of Spherical Parts with Small Curvature by NC Incremental Forming
    Xu Jiahui, Gao Lin, Shi Xiaofan, An Chuanhai
    2014, 25(23):  3164-3167. 
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    The forming process of small forming angle parts is one of the difficulties in NC incremental forming. Center bulge was generated easily during the forming process because of the pressure stress and springback. Small curvature spherical part was investigated through experiments, how to eliminate the center bulges was the key issue to improve the accuracy. The compensation methods, changing the forming tool and positive forming were used to optimize the forming size, and results show these methods are very effective to eliminate the center bulges and improve the accuracy through experiments, and all methods have their own advantage. So according to the accuracy requirements, different methods can be chosen in the actual production.

    Process Route Optimization of Production Line of Complex Products Based on Vulnerability Analysis
    Li Hua, Lu Suwei, Yang Ting
    2014, 25(23):  3168-3173. 
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    Complex process routes were contained in the manufacturing processes of complex products which possessed numerous equipment, and there was a high vulnerability with the production line of complex products. A directed weighted network model was constructed via applying the complex network theory. The topology characteristics of the production line net were described. Analysis results show that the uneven distribution of processes can lead to the vulnerability of the production line. An optimization model was proposed based on the deviation function of the process distribution. The feasibility and effectiveness in balancing the processes distribution by optimizing the process routes of the model presented was verified by a case of an aero-engine casing production line operation. The model can optimize the process routes.

    Multi-objective Genetic Algorithm for Parallel Machine Scheduling Problem with Outsourcing
    Sun Chaoping, Yang Ping, Li Kai,
    2014, 25(23):  3174-3179. 
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     This paper considered the parallel machine scheduling without sourcing, aiming to minimize both the total cost of outsourcing and the makespan simultaneously. On the careful analysis, a solution indicating method in a form of numeric string was designed, where every number represented the corresponding machine number of the fixed job. This method could reduce the solution effectively,thus improve the searching efficiency. Then a non-dominated sorting genetic algorithm with the elite strategy, PD-NSGA-Ⅱ was constructed, which could provide Pareto optimal solution sets of high quality to solve these multi-objective scheduling problems. Experimental results indicated that the PD-NSGA-Ⅱ algorithm could solve the scheduling problem within a reasonable period of time. The proposed PD-NSGA-Ⅱ algorithm, superior to SPEA, demonstrated an excellent performance in terms of solution quality and the computation time.

    Adaptive Optimization Scheduling of Knowledgeable Manufacture Oriented to Aircraft Engine Assembly Lines
    Wang Haoxiang, Yan Hongsen, Wang Zheng,
    2014, 25(23):  3180-3187,3194. 
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    To solve the problem of aircraft engine assembly scheduling in an uncertain production environment, an adaptive optimization scheduling algorithm of a knowledgeable manufacture oriented to an aircraft engine assembly lines was proposed, where a scheduling-policy solved mechanism combining Q learning and process simulation was used. A Q-learning adaptive scheduling model of aircraft engine assembly was built on the objective function of minimizing earliness penalty and completion time cost. Then four new scheduling rules were provided for assembly scheduling problem, four state features of aircraft engine assembly were defined for describing system states, and the proper reward function was designed for the objective function. Some simulation experiments indicate that the proposed algorithm outperforms other scheduling rules much in most cases, especially, better results are generally achieved with the frequently changes of task arrival rates to show good adaptive performance.

    Optimization Strategy of New Galfenol Force Sensing Structure and Energy Efficiency Based on Alternating Loads
    Shu Liang, Wu Guichu, Chen Dingfang
    2014, 25(23):  3188-3194. 
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    A new Galfenol force sensing structure was proposed, where the Galfenol alloy was taken as the sensing element. The two ends of the alloy were manufactured into the interfaces which could be assembled with external locking structures. Therefore the Galfenol rod could be subjected to both of compression and tensile. The sensing of the magnitude and direction of the external alternating loads could be implemented by measuring the induced voltage of Galfenol due to the change of the magnetic susceptibility. In order to increase the energy efficiency, a sealed structure was developed to optimize the flux path of the Galfenol force sensor. 2D and 3D finite element methods were used to study the distribution of the flux density and the energy efficiency of the proposed structure was compared with the open architecture path. Simulation and experimental results show that the uniformity of the distribution of flux density in Galfenol rod can be improved greatly by using the proposed sensing structure. Furthermore, the energy efficiency can be increased significantly over 50%. The optimization and the design of the proposed structure were verified with experiments by applying the alternating loads to the sensor structure.

    Machining Method for Coating on Huge Revolution Surfaces
    Chen Zhihong, Fang Hairong, Fang Yuefa
    2014, 25(23):  3195-3199,3238. 
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    This paper proposed a real-time machining method, which processed the foam coating on the surface of aircraft to be uniform in thickness,and with thin wall aluminum easily deforming cylindrical tankage. Non-contact distance measuring sensor was placed before the cutter. NC cutter path could be generated directly from discrete measured data points obtained with the measuring sensor. The machining problem for the thin-walled workpiece that was easy to be deformed was solved. In the period of cutter come to the measured points, data points acquisition, data processing and NURBS interpolation calculation should be finished. NURBS fast fitting method, micro-line and NURBS mixed interpolation were proposed based on fitting errors to meet the real-time machining requirements. Finally, experimental results verified the effectiveness of the machining method.

    Analysis on Characteristics of Milling Force in Micro-milling of ZrO2 Ceramics
    Bian Rong, He Ning, Li Liang, Qian Jun, Shi Zhenyu, Chen Mingjun
    2014, 25(23):  3200-3206. 
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    Aiming to the micro and precision machining of ceramics, micro-milling of fully sintered ZrO2 with diamond-coated micro end mills was carried out. The geometry characteristics of cutting zone in micro milling of ceramic materials were introduced. The reason of single edge cutting phenomenon was also analysed. The cutting force signals were measured by a dynamometer. The effects of cutting parameters and tool wear on the milling force were investigated respectively. The results reveal that when micro milling ceramics, the phenomenon of milling with only one cutting edge is more likely to occur due to small feed per tooth. The milling force in axial component, Fz, is bigger than the other two. It shows an uptrend while increasing the feed per tooth. With the increasing of cutting length, the milling forces show an increasing trend with some fluctuations due to aggravated tool wear. The increase rate of Fz is much biggerthan that of Fx and Fy.

    Research on Sliding Property of No-backlash Ball Precision Transmission Meshing Pair
    Yi Yali;An Zijun;Wang Haixia
    2014, 25(23):  3206-3211. 
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    In view of the influences of rolling and slipping of balls of engagement pair on the transmission accuracy of no-backlash ball precision transmission, applying engagement theory and converted mechanism kinematic analysis methods, the arc length difference was presented to represent sliding characteristics of engagement pairs. Sliding generating mechanism of balls during the transmission process was interpreted. Theoretical analysis mathematical model was established. The change rules of relative sliding velocity and sliding ratio of engagement pairs were analyzed,and variation curves were also plotted. The three-dimensional entity of no-backlash ball precision transmission was established, and kinematics simulation was carried out by using ADAMS. The results show that there is microscale sliding between meshing pairs. When the central plate engages with balls, sliding velocity and sliding rate is more obvious, the wear will be more serious.

    Nipped Configuration of Unconfined Particle Beds among Media Balls
    Mao Yalang, Sun Yi, Ji Shiming, Shan Jihong
    2014, 25(23):  3212-3215. 
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    Particles were mainly comminuted by ball mill within unconfined beds and nipped configuration was bound up with particle breakage. The experimental results and simulation show that the sizes of media balls and quartz particles have influences on the height of nipped bed, and the smaller ball and larger particle make the bed thin. A mathematical model that described the heights of nipped bed based on experimental data regression was proposed. The formula of the nipped range was deduced from the bed heights and self-locking of beds. The model and formula were validated using experimental data with good agreement.

    An Expansion of Functional Expression in General Profiles and Corresponding Scroll Compressor Plate
    Wang Licun, Zhang Guojin, Wang Xudong, Nie Xin, Zhu Ming, Song Lijun
    2014, 25(23):  3216-3220. 
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    To make the generation process of scroll compressor plate based on general profiles more simple and easy to implement, the general scroll profile equation was expanded through Taylor theory and two different vector forms of conjugating scroll profiles were given according to analytic geometry-vector method, also a generation process in building scroll plate and a specific design using MATLAB were given. Using vector method to study scroll profiles with conjugating relationship can both change shape of scroll profiles through numerical operations and illustrate conjugating theory by its geometrical direct-vision. The expanded general profiles equations integrate all kinds of scroll profiles, and avoid complex traditional operations, which contributes to the research on coefficient optimization.

    Analyses of Wrinkling in Flange Region and Rupture in Axisymmetric Deep Drawing under Plane Stress Model
    Qin Siji, Yang Li, Gai Binbin
    2014, 25(23):  3221-3226. 
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    Plane stress and plane strain assumptions were adopted to make comparisons respectively in the stress distribution of the flange region in the axisymmetric deep drawing. The values of radial stress differ a little, while the values of circumferential stress vary in a large range, which were calculated under these two conditions. It can be shown from the finite element simulation that the analytical results of the plane stress assumption are very close to the simulation results, which means the plane stress assumption is closer to the actual situation than the plane strain assumption. Wrinkle instability conditions in the flange region and rupture instability conditions of cylindrical parts were constructed under the plane strain assumption. And the formula of critical BHF was deduced from the assumption. The project of critical BHF with drawing position for a specific deep drawing problem was obtained. The analysis results are useful for understanding of the characteristics of different deformation regions in deep drawing process. Also,the analyses are helpful to set up more reliable criterions of wrinkling and rupture. Meanwhile, it is more accurate to predict the forming defects and critical BHF.

    Impact of Residual Stress Relaxation and Autofrettage Pressure on In-service Pressure Vessel Safety
    Chen Haihui, Zeng Yingying, Zhong Hantong
    2014, 25(23):  3227-3231. 
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    In order to determine the impacts of residual stress relaxation and autofrettage pressure on the in-service pressure vessel safety, the relaxation rule of the residual stress was showed by the test results. The equivalent stress distributed along the vessel wall was calculated under the coupling conditions of the operating pressure and residual stress; the safety coefficient was simulated under the different operating pressures and autofrettage pressures, then the optimum autofrettage pressure was deduced. In this case, a high-pressure polyethylene reaction tube was serviced for 10 years. The results show that the vessel tangential stress in the near wall region decayes from -600MPa to -333MPa fast with the attenuation rate reaching 45%. Attenuation was measured in the elastic region and the residual stress peak location was relocated but a little change in its peak value. For the auto-frettaged pressure vessel under the coupling conditions of operating stress and residual stress, with the residual stress relaxation, the equivalent stress of inner wall surface is increased and the largest equivalent stress is at the junction of the elastic and plastic body, where the safety factor should be calculated. According to this case polyethylene pipe size, the operating pressure is at 180MPa, 280MPa, 380MPa respectively, then the best autofrettage treatment pressure is at 606MPa, 677MPa, 743MPa respectively, the safety factor is larger 16%, 26%, 37% respectively than residual stress all attenuation to 0. With the higher operating pressure, the vessel safety factor increased by optimal autofrettage process is higher, but impact caused by the residual stress attenuation is greater.

    Identification of Mining Road Roughness Based on GA-BP Neural Network
    Gu Zhengqi, Zhu Yifan, Zhang Sha, Ma Xiaokui
    2014, 25(23):  3232-3238. 
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    BP neural network optimized by GA was used to identify the mining road. A fourteen degree-of-freedom vehicle vibration model was set up. The vehicle seat acceleration obtained by simulation was regarded as an ideal input sample of neural network, and the fitting road roughness was regarded as an ideal output sample of neural network based on inverse transformation principles, then the nonlinear mapping model between them was built by network training. Road roughness was identified under the conditions of different grade roads through fitting, various pit roads and different loads of dump truck. Identification ability was verified for complex mining roads due to high correlation coefficient and small relative error in this method. The accuracy of the method was verified through vehicle road test. Compared with simulation results of ride comfort under common C-class roads, it is shown that identification road is more closer to actual one, so as to achieve the purpose of improving the simulation accuracy of the models.

    Modeling and Analysis of Energy Consumption for Air Suspension System with Closed-loop Air Circuit
    Jiang Hong, Qian Kuan, Qiu Yadong, Xu Xing
    2014, 25(23):  3239-3244. 
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    The energy consumption during charging and discharging processes of a closed-loop air suspension system with high and low pressure chambers was studied herein. Based on the thermodynamics theory and vehicle dynamics, the charging and discharging models of the closed-loop air suspension system were developed and simulated in the Simulink environment. The simulation model was validated by the charging and discharging experiments of the air springs on the half-vehicle system. In order to study the ways of energy loss of the closed-loop system, the compressed gas effective energy which means the work made by the compressed gas to the external atmosphere was adopted and quantitative calculations were completed during the processes of charging, discharging and boosting. The simulation results indicate that during the charging process the energy consumption increases along with the rising of the pressure in the high pressure chamber. However, energy consumption in both of discharging and boosting processes reduces along with rising of the pressure in the low pressure chamber. More energy can be saved by using closed-loop system with high and low pressure chambers comparing to the open-loop system under same circumstances.

    Review on Scheduling Algorithms for MOFJSP
    Peng Jiangang, Liu Mingzhou, Zhang Mingxin, Zhang Xi
    2014, 25(23):  3244-3254. 
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    A mathematical model and related definitions of MOFJSP were introduced and the related theories and the research fruits of MOFJSP were summarized. The emphasis was focused on review both of the computational intelligent algorithms and the intelligent search methods. Some future research directions and contents of optimization scheduling algorithms were pointed out and suggestions of related researches in the future were proposed.

    Review and Development Trends of Deep-sea Mineral Resource Core Sampling Technology and Equipment
    Liu Deshun, Jin Yongping, Wan Buyan, Peng Youduo, Huang Xiaojun
    2014, 25(23):  3255-3265. 
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    Seafloor rock drill is the necessary equipment for marine geologic and environmental investigation. The present situations of deep-sea mineral resource core sampling technology and equipment were summarized, and the performance, structure and technology characteristics of several kinds of typical seafloor rock drill were focused on. The supporting and leveling mechanism technology, core sampling technology, drill string making and breaking and drill rods storage magazines technology, hydraulic system and pressure compensation technology, high voltage power supply and high-speed data communication technology by armored power & communication cable and launch and recovery technology of key technological problems of seafloor rock drill were analyzed. Based on analyses of the development of seafloor rock drill, it will develop into large-size, multiuse, intellectualization, professionalization, facilitation and truth-preserving sampling.